GB2501052A

GB2501052A - Modular aircraft power supply unit

Info

Publication number: GB2501052A
Application number: GB1117520.5A
Authority: GB
Inventors: Arthur Jerrett; Luke Poradowski; Alan Mills
Original assignee: ALMEC EAS Ltd
Current assignee: ALMEC EAS Ltd
Priority date: 2011-10-11
Filing date: 2011-10-11
Publication date: 2013-10-16
Also published as: GB201117520D0

Abstract

A modular aircraft power supply unit has an input unit 20 having an electrical source; a housing 10 having output compartments 14,16 receiving removable output units 30,40 for supplying electrical power to external devices; and a controller for distributing electrical power between the input and output units. An input compartment 12 may receive the input unit 20. Input and output units may register with the controller and ribs can guide units into their compartments. Input unit 20 and output units 30,40 can have respective data input and outputs (fig 2), data being distributed between input and output units by the controller. The input and output units can use a single ended primary inductor DC to DC converter (fig 3, 23,24) and include EMC shielding and ESD protection.

Description

AIRCRAFT POWER SUPPLY UNIT

This invention relates to an aircraft power supply unit.

Aircraft power systems, including aircraft power supply units, are presented with a number of design challenges. Power generation in an aircraft typically produces alternating current at a much higher frequency than used in ground-based (e.g. household, industrial, or commercial) environments. Furthermore, aircraft power systems must accommodate a wide range of operating conditions, for example in the event of engine failure, the power system may need to revert to backup power sources. The available power may therefore be severely limited. Thus, aircraft power supply units seldom use off-the-shelf technologies.

Furthermore, it is imperative that other electrical systems in the aircraft, e.g. the pilot's navigation system, are not interfered with. Therefore, minimal disturbance to the supply (i.e. a high power factor with low harmonic distortion) and low conducted and radiated electromagnetic interference are preferable features but present additional design challenges. Furthermore, it is important for the components of the aircraft power systems to be light, compact, and generate minimal heat.

Aircraft power supply units must cooperate with a wide variety of equipment on an aircraft.

For example, aircraft power supply units must generate power at the required levels for powering control systems, actuators, entertainment systems and air conditioning systems.

All these different devices have differing electrical requirements. Therefore, either the aircraft power supply unit is tailor-made, or the aircraft power supply unit is built with a range of power conversion circuitry to serve multiple applications.

Neither option is satisfactory. That is, if the aircraft power supply unit is tailor-made for the external device, and the external device is changed, the power supply unit must also be changed. This adds to the cost and maintenance lime of upgrading or servicing an aircraft.

Furthermore, if the aircraft power supply unit is built to serve multiple applications, then it must include a wide range of power conversion circuitry, which adds to the cost of building the unit, increases the amount of heat generated, and increases the size of the unit.

A first conventional aircraft power supply unit uses a linear architecture, producing a direct current at the required voltage using a transformer and rectifier. This arrangement produces an acceptable level of electromagnetic interference. However, it is heavy and inefficient.

A second conventional aircraft power supply unit uses switched-mode technology, having a transformer operating at a much higher frequency (typically around 90kHz). This arrangement is lighter, smaller and has a greater efficiency rating than the first conventional aircraft power supply. However, the high switching frequency generates conducted and radiated emissions that have the potential to disrupt other electrical systems in the aircraft.

Therefore, the second conventional aircraft power supply unit requires careful design of filtering and shielding in order to meet the stringent emissions requirements, which increases the manufacturing cost and complexity of the device.

In aircraft cabins, power supply units are presented with additional problems. Naturally, the power supply unit needs to have a cooling system to prevent overheating of the electronics and to ensure the surface temperature does not exceed a threshold such that it may cause injury. However, such power supply units are not able to rely on forced air-cooling or cooling fans. It is often necessary for an external protective shield to be provided around a conventional power supply unit in order to prevent accidental contact with hot surfaces.

However, this adds to the weight, size and maintenance cost of the installed unit.

It is therefore desirable to alleviate some or all of the above problems.

According to a first aspect of the invention, there is provided an aircraft power supply unit, including an input unit having an electrical source, comprising a housing, having an output compartment; an output unit, having a power output for supplying electrical power to an external device, wherein the output compartment is configured to removably receive the output unit; and a controller, for distributing electrical power between the input unit and first output unit.

Therefore, a power supply unit of the present invention is a modular design. That is, the output unit may be changed for a unit with different electrical characteristics. Thus, the power supply unit of the present invention is very versatile, and may decrease the maintenance time when servicing or upgrading an external device on an aircraft. For example, if an aircraft seat actuator is changed for one having different power requirements, then the output unit may simply be changed to match those requirements. This alleviates the need either to change the whole power supply unit (in the case of the prior art tailor made power supply units), or alleviates the need for power supply units to have a wide range of power conversion circuitry, which are larger, generate more heat and are more expensive.

The power supply unit of the present invention may therefore be smaller, generate less heat and be less expensive to maintain.

The housing may include an input compartment, configured to removably receive the input unit. Thus, the modular design of the power supply unit may also include removable input units. This further enhances the adaptability of the power supply unit.

Optionally, the output compartment is one of a plurality of output compartments, and the output unit is one of a plurality of output units, each having a power output for supplying electrical power to an external device, wherein the plurality of output compartments are configured for removably receiving the plurality of output units, and the controller is for distributing electrical power between the input unit and the plurality of output units.

Therefore, the power supply unit may be used to distribute power between multiple devices connected to each output unit. For example, a first output unit may be connected to a first seat, and a second output unit may be connected to a second seat.

Preferably, the input unit includes a data input, and the output unit includes a data output, and the controller is for distributing data between the input unit and output unit. Therefore, the input unit and output unit, and any devices connected thereto, may communicate with each other. For example, a passenger may change the settings on his seat position through his in flight entertainment system if they are both connected to the power supply unit and the command is communicated from the in flight entertainment system to the seat actuators via the controller. Furthermore, a sub-controller on either the input or output unit may monitor diagnostic or fault events in the units and may communicate this with an external control system.

Preferably, the housing includes one or more guide members for guiding the input and/or output units into the compartments and registering with the controller. This provides a simple way of inserting the input and output units such that they may register and connect with the controller. The housing may also include locking mechanisms to lock the input and output units in place when fully inserted.

The power conversion circuits for the input and output modules may be designed to convert between an external power line and an internal power of the power supply unit. The input unit and/or output unit may use a single-ended primary-inductor converter for DC-to-DC conversion. Advantageously, single-ended primary-inductor converters may convert the input DC voltage to a higher, lower or equal output DC voltage, and they isolate the input voltage from the output voltage, which is beneficial in avionics applications. This enhances safety as a fault, such as a short-circuit on an output line, cannot be carried over to the power input. Furthermore, the isolation provides a means of eliminating very fast transient spikes that would otherwise be very difficult to eliminate using surge arrestors or transient voltage suppression diodes.

Furthermore, the input unit and/or output unit may include EMC shielding and/or ESD protection.

Embodiments of the invention will now be described, by way of example, and with reference to the drawings in which: Figure 1 is a perspective view of a power supply unit of an embodiment of the present invention; Figure 2 illustrates a flow of signals through the power supply unit of Figure 1; Figure 3 illustrates a flow of signals through an input unit of the power supply unit of Figure 1; and Figure 4 illustrates a flow of signals through an output unit of the power supply unit of Figure 1.

An embodiment of the invention will now be described with reference to Figures 1 to 4. An aircraft power supply unit 1 is provided, having a housing 10, an input unit 20, a first output unit 30 and a second output unit 40.

The housing 10, which has an open front side and an opposing rear side, includes a first compartment 12, a second compartment 14 and a third compartment 16. The first, second and third compartments 12, 14, 16 are configured to removably receive the input unit 20, first output unit 30 and second output unit 40 respectively by insertion of the units along direction X'. In this embodiment, the housing 10 has a plurality of internal ribs (not shown) between each compartment to guide the units into their compartments. The housing 50 also includes a locking mechanism (not shown) to lock the units in their compartments when each unit is fully inserted.

In this embodiment, the input unit 20, first output unit 30 and second output unit 40 are all sealed to form a self-contained unit, having EMC shielding, ESD protection and heat dissipation.

It is beneficial to minimise electro-magnetic (EMC) emissions in electronic equipment for aircraft in order to prevent interference with communications, navigation and other essential aircraft systems. Different sections of the PSU circuitry will generate different electro-magnetic emissions. Those emissions may be received by other sections of the PSU circuitry. This can result in increased conducted and/or radiated emissions of the overall unit. In this embodiment, the solution is to screen the portion of circuitry generating the emissions from the rest of the circuits, by enclosing the input and output units in an electrically conductive housing (typically metal or metallised plastic, according to the application). The housings are grounded, thereby providing EMC shielding of each section of the power supply unit. A further benefit of this arrangement is that the housings may be used as heat-sinks to dissipate excess heat from those components that could otherwise overheat.

The housing 10 also includes a controller 50 (not visible in Figure 1) located on an internal face of the opposing side. The controller 50 has an input interface, including a power input port and a data input port; a first output interface, including a first power output port, a second power output port, and a data output port; and a second output interface including a first power output port, a second power output port, and a data output port (all not visible in Figure 1).

The input unit 20, first output unit 30, and second output unit 40 each have a corresponding interface for connecting with the input interface, first output interface and second output interface respectively. Therefore, the input unit 20 includes a corresponding power input port and a corresponding data input port, and the output units 30, 40 include corresponding first power output ports, second power output ports, and corresponding data output ports.

The controller 50 and each unit are configured such that the interfaces register and connect as the units are fully inserted into their compartments.

A flow of electrical signals (e.g. power and data signals) in the aircraft power supply unit 1 will now be described with reference to Figures 2 to 4. In this embodiment, the input unit 20 receives a power signal (e.g. at 11 5Vac at 400Hz) from an external source at the power input port "Powere,ztinput", and a data signal from an external device (e.g. using the RS232 standard) at the data input port "Data1".

As shown in more detail in Figure 3, the input unit 20 includes a circuit breaker 21, filtering, monitoring and power factor correction circuitry 22, a first power converter 23, a second power converter 24 and an input sub-controller 25. The second power converter 24, which may supply power at a lower voltage than the first power converter 23, provides power for the input unit sub-controller 25. The input unit 20 includes a first electrical path, starting at point 100, where the power signal is received at the power input port The power signal passes through the circuit breaker 21 and the filtering, monitoring and power factor correction circuitry 22, which both operate in their usual manner.

At point 102 of the electrical path, the power signal may pass through point 103, to a first input power converter 23, or point 104, to a second input power converter 24. In an alternative embodiment of the invention, power to drive the sub-controllers may be derived from the output of the first power converter 23 (i.e. at point 105).

In this embodiment, the first input power converter 23 includes a rectifier, for converting the power signal to an interim level, typically in the range 150 to 200Vdc. For the remainder of this description, this power signal will be referred to as a 200Vdc signal. The 200Vdc signal passes from point 105 to a first power output port "Powertjrstoutput" on the input unit's 20 interface with the controller 50.

In this embodiment, the second input power converter 24 also includes a rectifier, for converting the power signal to a lower voltage signal, typically in the range of 3 to l4Vdc.

For the remainder of this description, this power signal will be referred to as a l4Vdc signal.

The 1 4Vdc signal passes from point 106 to a second power output port Powersecofldouput" on the input unit's 20 interface with the controller 50, and to the input sub-controller 25.

The input unit 20 also includes a second electrical path, starting at point 110, where the data signal is received at the data input port The data signal is processed by the input sub-controller 25 (as described below), and passes to a data output port Data011" on the input unit's 20 interface with the controller 50.

Referring back to Figure 2, the 200 Vdc signal, l4Vdc signal and the data signal pass to the controller 50 via the interface between the controller 50 and the input unit 20. As both the first output unit 30 and second output unit 40 are also registered with the controller 50, the controller 50 distributes the three signals to the first output unit 30 and the second output unit 40. In this embodiment, the controller 50 also provides power return and grounding connections between the input unit and the first and second output units.

The first output unit 30 will now be described with reference to Figure 4. The skilled reader will understand that the second output unit 40 is substantially similar. The first output unit 30 has a first output power converter 31, a second output power converter 32, a first switching and monitoring module 33, a second switching and monitoring module 34 and an output sub-controller 35.

The first output unit 30 receives the 200 Vdc power signal, l4Vdc power signal and the data signal, via the interface with the controller 50 and first power input port "PowerfflPU", a second power input port "PowerSOCOfldflPUl", and an data input port "Data1" respectively.

The first output unit 30 has a first electrical path, starting at point 200, where the 200 Vdc signal is received at the first power input port Powerfjrstjflput. The 200 Vdc signal may then pass through point 201, to the first output power converter, or point 202 to the second outpupt power converter 32.

In this embodiment, the first output power converter is a DC-to-DC converter, for converting the 200Vdc signal to a 2BVdc signal. The 2BVdc signal passes from point 203, through the first switching and monitoring module 33 (which operates in a usual manner), to a first power output port "Powerjjrstouipui" In this embodiment, the second output power converter is also a DC-to-DC converter, for converting the 200Vdc signal to a l2Vdc signal. The l2Vdc signal passes from point 204, through the second switching and monitoring module 34 (which also operates in a usual manner), to a second power output port Powersefldoutput".

The first output unit 30 also has a second electrical path, starting at point 205, where the l4Vdc signal (from the second input power converter 24 of the input unit) is received at the second power input port Powersecofldjflput", and a third electrical path, starting at point 206, where the data signal is received at the data input port The l4Vdc signal provides power for sub-controller 35 (which is described below), which sends and receives data via output port Data011".

The first output power port Fowerfjrstoutput, second output power port Powergeoofldoulpul and the data output port may be connected to one or more external devices, e.g. an aircraft seat actuator or an in-flight entertainment system, for powering and controlling the external devices.

The sub-controllers 25, 35 will now be described in more detail. The sub-controllers 25, 35 allow the input unit 20, the first output unit 30 and the second output unit 40 to communicate with each other, and allow a first external device connected to the input unit 20, a second external device connected to the first output unit 30 and a third external device connected to the second output unit 40 to communicate with each unit and with each other (that is, the data transmission via the interface between each unit and the controller 50 is bi-directional, and the controller 50 is configured to distribute the data signals between each unit). In a variation of the invention the sub-controllers 25, 30 may form part of the controller 50, with data from outside being passed through the input unit 20 and output units 30, 40.

Therefore, the external devices may send commands to each other. For example, the first output unit may be connected to an in flight entertainment system, and the second output unit may be connected to an aircraft seat actuator, and the user may input an appropriate command (e.g. recline seat) to the in flight entertainment system to cause the aircraft seat actuator to move (such that the aircraft seat reclines), which is communicated to the aircraft seat actuator via the controller 50. In an alternative embodiment, the in flight entertainment system may be powered independently, and the input unit may receive data signals from the in flight entertainment system via the data input port which may be communicated to a device connected to one of the output units.

Furthermore, an aircraft's central cabin system may be connected to the input unit 20, and the first or second output unit may be connected to an in flight entertainment system, and the aircraft central control system may command the in flight entertainment system to display information to the seat occupant (e.g. to put on their seat belt in the event of turbulence), which is communicated to the in flight entertainment system via the controller 50.

Furthermore, the sub-controllers are configured to monitor the various elements of the aircraft power supply unit 1. For example, the input sub-controller 25 may monitor the power level at the power output ports on the input unit, and the output sub-controller 35 may monitor the power consumption of an external device. Therefore, the sub-controllers may be able to detect a fault condition in the power supply unit 1, and shut down the appropriate element in response. For example, in the event the power consumption of an external device exceeds a threshold level, the sub-controller 35 may shut-down the output unit or output port associated with the external device, or may shut-down the external device by sending the appropriate command via the data output ports. Furthermore, the power supply unit 1 may communicate diagnostic information about any one of the units or an external device connected to the unit to a diagnostic device (e.g. the aircraft's central maintenance system).

In an optional embodiment of the aircraft power supply unit, a power converter of the input unit or the output unit is a single-ended primary inductor converter (SEP10). This converter is particularly suitable for avionics applications, as the SEPIC is capable to providing an output voltage that is higher, equal or lower than the input voltage, and it is also possible to isolate the output voltage from the input voltage. This enhances safety because a fault, such as a short-circuit on the output line, cannot be carried over to the mains output.

Furthermore, the isolation provides a means of eliminating very fast transient spikes that would otherwise be almost impossible to eliminate using surge arrestors or transient voltage suppression diodes.

The skilled reader will understand that the present invention is not limited to the arrangement of two output units. That is, any number of output units (typically one to three) may be used, and the controller may be adapted to distribute the power and data signals accordingly.

The skilled reader will also understand that the invention is not limited to the use of the specific electrical signals mentioned above. That is, although in most avionics situations the input power signal will be either ll5Vac at 350 to 800Hz or 28Vdc, any suitable input power signal may be used, for example 24OVac at 50Hz for a ground-based application. Also, the output signals are not limited to those specified above. That is, the aircraft power supply unit may be adapted to output any power signal suitable for any external device. Furthermore, the data signals need not be of the RS232 standard, but may be any suitable standard for this application, e.g. Arinc, RS422, RS485, 120, CANBUS, USB, etc. In the embodiment described above, the first and second output power converters are DC-to-DC converters in order to provide a different voltage from that provided by the first converter (e.g. 2BVdc and l2Vdc). However, the skilled person will understand that the first and/or second power converters may instead be inverters, for converting the power from DC to an AC signal. Applications requiring an AC output may be achieved in a separate output unit, which may only have one output converter.

The skilled reader will also understand that the present invention is not limited to receiving an input power signal from an external source (e.g. a generator or battery). That is, the power supply unit may have an integral power source (e.g. a battery) either embodied in the input unit or elsewhere on the power supply unit.

The skilled person will also understand that the number of power converters used in the above embodiment is merely one example within the scope of the invention. That is, the power supply unit only needs to have a single power converter, either embodied on the input unit or the output unit, for converting the input power signal.

Furthermore, the skilled person will understand that it is not essential for the input and output units to have EMC shielding, ESD protection and heat dissipation. Rather, the housing may have these features, or they may be omitted completely. However, the input and output units preferably have these features as they reduce electromagnetic interference and help to prevent overheating of the power supply unit.

The skilled person will also understand that the present invention is not limited to the use of sub-controllers on the input and output units. However, these are preferable as they allow intelligent monitoring of the input and output units and for controlling the data flowing between the external devices and input and output units. The skilled person will also realise that the circuit breaker, filtering, power factor correction, monitoring and switching modules are all non-essential features of the present invention.

The skilled person will also realise that the guide members previously mentioned (the ribs) and the locking mechanism are both non-essential features of the present invention.

The skilled person will also understand that the input unit may be integral with the power supply unit, such that only one or more output units are removeable.

The skilled person will realise that any combination of features is possible without departing from the scope of the invention, as claimed.

Claims

CLAIMS1. An aircraft power supply unit, including an input unit having an electrical source, comprising a housing, having an output compartment; an output unit, having a power output for supplying electrical power to an external device, wherein the output compartment is configured to removably receive the output unit; and a controller, for distributing electrical power between the input unit and first output unit.
2. An aircraft power supply unit as claimed in Claim 1, wherein the housing includes an input compartment, configured to removably receive the input unit.
3. An aircraft power supply unit as claimed in any preceding claim, wherein the output compartment is one of a plurality of output compartments, and the output unit is one of a plurality of output units, each having a power output for supplying electrical power to an external device, wherein the plurality of output compartments are configured for removably receiving the plurality of output units, and the controller is for distributing electrical power between the input unit and the plurality of output units.
4. An aircraft power supply unit as claimed in Claim 1, wherein the housing includes an output unit guide member for guiding the output unit into the output compartment and registering with the controller.
5. An aircraft power supply unit as claimed in any one of Claims 2 to 3, wherein the housing includes a plurality of guide members for guiding the units into their compartments and registering with the controller.
6. An aircraft power supply unit as claimed any preceding claim, wherein the input unit includes a data input, and the output unit includes a data output, and the controller is for distributing data between the input unit and output unit.
7. An aircraft power supply unit as claimed in any preceding claim, wherein the input unit uses a single-ended primary-inductor converter for DC-to-DC conversion.
8. An aircraft power supply unit as claimed in any preceding claim, wherein the output unit uses a single-ended primary-inductor converter for DC-to-DC conversion.
9. An aircraft power supply unit as claimed in any preceding claim, wherein the input unit includes EMC shielding and/or ESD protection.
10. An aircraft power supply unit as claimed in any preceding claim, wherein the output unit include EMC shielding and/or ESD protection.
11. An aircraft power supply unit as herein described with reference to and as shown in any one of the accompanying drawings.